🌌 #9: Second Try on M101

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Some targets really make you work for it — and M101, the Pinwheel Galaxy, is one of them.

I had previously imaged this beautiful but faint spiral with an Olympus E-5II, but after switching to the Olympus E510, I wanted to revisit the same target for a comparison between the two cameras. In the meantime, I’d been experimenting with better polar alignment. SkyWatcher mounts offer a neat trick: you can refine polar alignment without using a polar scope by slewing to an alignment star and letting the mount deliberately push it off-center. You then use the ALT/AZ knobs to bring it back into the center of the field of view. Simple, but surprisingly effective.

After fiddling with this tool for a while, I managed to improve my alignment enough to achieve 120-second exposures, even on my small and frankly overloaded SkyWatcher EQ3-Pro. That felt like progress!

Unfortunately, about half the frames ended up with star trails. Guiding would have helped, but I did what I could — capturing 40×120s exposures in total. After culling the unusable frames, I was left with 17 clean lights, totaling 34 minutes of integration time. Not ideal for a target as faint and detailed as M101, but I pressed on. To support the data, I also added 15 darks and 30 bias frames to reduce the background noise.

🔧 Processing Challenges

Despite a darker moon phase than my first attempt and double the exposure time, M101 remained barely a blip on the histogram — a faint spike buried in the noise. Stretching the data was difficult and frustrating. Highlights blew out quickly, the stars bloated, and the background noise took on a life of its own.

You can make out the core and some spiral structure in the arms, but it still falls far short of showing the true beauty of this galaxy. Comparing this second attempt to the first, I could see improvement — but not yet success.

đŸ“· Tech Specs

  • Lights: 17 × 120s
  • Darks: 15 × 120s
  • Bias: 30
  • ISO: 800
  • Mount: SkyWatcher EQ3-Pro (unguided)
  • Camera: Olympus E510

🔭 Conclusion

I need to come back to this one — properly. Next time, I’ll need guiding, a dark, moonless sky, a better camera, a light pollution filter, and a full night of exposure time. M101 deserves to be captured in all its faint, glorious detail, but that requires more than I currently have in my toolbox.

This galaxy may be elusive, but I’m not giving up. One day, I’ll get it right.

Clear skies,
Chris